Loading unit for telephone systems.



W. FONDILLER.

LOADING UNIT FOR TELEPHONE SYSTEMS.

APPLICATION FILED DEC. so. 1916.

1 ,253,365, Patented Jan. 15, 1918.

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UNITED STATES PATENT OFFICE.

WILLIAM FONDILLER, OF NEW YORK, N. Y., ASSIGNOR TO WESTERN ELECTRIC COM- PANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

LOADING UNIT FOR TELEPHONE SYSTEMS.

Specification of Letters Patent.

Patented Jan. 15, 1918.

Application filed December 30, 1916. Serial No. 139,984.

To all whom it may concern:

Be it known that I, IVILLIAM FONDILLER, a citizen of the United States, residing at New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Loading Units for Telephone Systems, of which the following is a full, clear, concise, and exact description.

This invention relates to loading units for telephone systems, and particularly to core structures for a loading unit adapted for the simultaneous loading of two physical circuits and their derived or phantom circuit.

In an arrangement described and claimed in an application of J. B. Speed, Serial No. 88,072, filed March 31, 1916, and assigned to the same assignee as the present application, the simultaneous loading of two physical circuits and their derived phantom circuit is provided for by means of a loading unit characterized by two toroidal core members intersecting on a common diameter.

' In said loading unit, the two line windings individual to one of the physical circuits are located on opposite halves of one toroid, and the line windings individual to the other physical circuit are located on opposite halves of the other toroid. Each physical circuit is thus loaded independently of, and without interference with, the other physical circuit. Furthermore, when phantom circuit currents flow through the windings of this loading unit, the distribution of flux is such as to load the phantom circuit in addition to the physical circuits.

It is an inherent characteristic of a loading unit of the kind just described that the mutual inductances between all line windings are very nearly equal, as a result of which the phantom circuit inductance is only fifty per cent. of the physical circuit inductance. This is due to the fact that for phantom circuit operation the two line windings of each toroid are connected in parallel and the two parallel circuits thus formed are connected in series. The resultant inductance therefore is equal to that operative in a single line winding; that is, the self-inductance of a line winding plus its mutual inductance to an adjacent winding. The mutual effects of the remaining windings bein in opposite directions cancel each other. The physical circuit inductance on the other hand is that due to two line windings in series,

which in effect is the sum of the two selfinductauces plus twice their mutual inductance. It has been found in practice, however, taking into consideration the mutual capacity of the phantom circuit as compared with the mutual capacity of the physical circuit, that, in order to load a phantom circuit to the best advantage, its inductance should be approximately sixty per cent. of the physical circuit inductance.

In a patent to George A. Kelsall, No. 1,238,153, dated August 28, 1917, and assigned to the same assignee as the present application, an improvement upon the invention covered by the application of James B. Speed, hereinbefore mentioned, is described and claimed. Said Kelsall invention has for its general object to modify the relation of the physical circuit inductance to the phantom circuit inductance, so that the latter is approximately sixty per cent. of the former, thereby satisfying the requirement before mentioned; and said invention is characterized by the provision in the magnetic structure of gaps of high reluctance which are so located that they increase the reluctance of the paths traversed by the physical circuit flux, but do not substantially increase the reluctance of the paths traversed by the phantom circuit flux.

The present invention may be considered an improvement upon the inventions covered by the aforesaid applications of J. B. Speed and G. A. Kelsall; and is characterized by the provision in the magnetic structure of gaps of high reluctance in the form of slots extending diagonally across the core members at their points of juncture. Among the advantages of this structure over the structures described and claimed in said Kelsall application, are decreased susceptibility of the phantom circuit to the effects of superimposed telegraph currents and greater ease in obtaining the desired ratio between physical circuit inductance and phantom circuit inductance. The first mentioned advantage is due to the fact that in this structure a gap is interposed in the path of the phantom circuit flux as well as in the path of the physical circuit flux.

The invention will be understood from the following description taken in connection with the accompanying drawing, in which Figure 1 isa perspective view of the magnetic structure of a loading unit embodying one form of the invention; and Fig. 2 is a perspective view of another form of magnetic structure also embodying the invention.

The core members shown in Figs. 1 and 2, and hereinafter described, may be of any suitable magnetic material. For example, they may conveniently be formed of finely divided iron, the individual particles of which are insulated from one another, the core material being molded by high pressure, in the manner described and claimed in an application for patent of James B. Speed, Serial No. 89,409, filed April 6, 1916. and assigned to the same assignee as the present application. Such core material may be readily worked to the desired shapes by molding and cutting.

Referring to Figs. 1 and 2, the core structures for loading units therein shown comprise in efiect two toroidal core members 1 and 2 arranged to intersect at right angles on a common diameter. It will be under- StOOd. that opposite halves of core member 1 are intended to carry windings included in the line conductors of one physical circuit; and that the opposite halves of core member 2 are intended to carry windings included in the line'conductors of the other physical circuit; as described in the aforesaid application of J. B; Speed, Serial No. 88,072. It will also be understood that the parts may be held together many suitable manner.

In the core structure of Fig. 1, gaps of high reluctance are provided in the form of slots extending diagonally across the core members 1 and 2 at their points of juncture, said slots being in planes substantially at right angles to one another. Said slots may be filled with any suitable non-magnetic material such as blocks or sheets of fiber 3 and 4.

In a core structure shown in Fig. 2, the

,1 gaps of high reluctance located at the points of juncture of the core members 1 and 2, are in the form of crossed slots extending diagonally across said core members. Said slots ;may be filled with non-magnetic material. I such as fiber of the form indicated at 5 and 6.

As explained in the aforesaid application of J. 15. Speed, Serial No. 88,072, the physical circuit flux due to windings on core memis confined to that core member. And the phantom circuit flux due, to said windings all passes from one point of juncture through A the two halves of core'member 1 to the other juncture, and back through the two halves of the othercore member 2 to the first mentioned juncture. In Figs. 1 and 2, the paths of the physical circuit flux are indicated by arrows made with full lines; and the paths of the phantom circuit flux are indicated by arrows made with dash lines.

It will be obvious from the foregoing descrlption and from the drawing, that the gaps of high reluctance of the two forms shownwill increase the reluctance of the paths traversed by the physical circuit flux to a much greater extent than they will increase the reluctance of the paths traversed by the phantom circuit flux, thereby reducing the mutual inductances of the physical circuit more than those of the phantom ci cuit. By suitably proportioning said g it is possible to make the reluctance of path traversed by the phantom circuit flux such that the inductance operative in the phantom circuit is substantially sixty per cent. of that operative in each of the physical circuits, which is the relation desired as hereinbefore explained.

It will be understood that while in the drawing core structures are shown in which the core members are substantially square in cross-section, they may, if desired, have other cross-sectional forms. The term to roid used herein, is intended to refer to a ring 01- any desired cross-section. It will also be understood that instead of rings, rectangular or other forms of frames and closed figures might be employed, and that. for want of some broader expression, the term toroid is used to denote all such structures.

hat is claimed is:

1. A loading unit having a plurality of core members each in the form of a closed figure, said members intersecting at a plural ity of points and being provided with gaps of high reluctance in the form of slots extending diagonally across said members at the intersections.

2. In a loading unit, two toroidal core members intersecting on a common diameter and having gaps of highreluctance therein in the, form of slots extending diagonally across saidmembers at their points of junc ture.

3. In a. loading unit, two toroidal core members intersecting on a common diameter and having gaps of high reluctance therein in the form of crossed slots extending diagonally across said members at their points of.

juncture.

In witness whereof, I hereunto subscribe my name this 29th day of December A. D..

NVILLIAM FONDILLER.

I Sopies oi thispatenemay be obtained for five cents each, byaqldressing the Commissioner of=Patents,

' Washington, D. O. 

